Adhesion enhancement of diamond-like carbon thin films on Ti alloys by incorporation of nanodiamond particles

Coating adherent diamond-like carbon (DLC) thin films directly on Ti alloys is technologically difficult. This research incorporates nanodiamond particles to form a diamond/DLC composite interlayer to enhance the adhesion of DLC thin films on Ti6Al4V substrates. Initially, nanodiamond particles were deposited on Ti6Al4V substrates by microwave plasma enhanced chemical vapor deposition from a methane–hydrogen gas mixture. A DLC thin film was then deposited, on top of the nanodiamond particles, by direct ion beam deposition. Scanning electron microscopy, Atomic force microscopy, X-ray Diffraction and Raman spectroscopy were used to characterize the microstructure and chemical bonding of the deposited particles and films, and Rockwell indentation testing was used to evaluate the adhesion of the deposited films. The results indicate that the pre-deposited nanodiamond particles significantly enhance the interfacial adhesion between the DLC thin film and the Ti6Al4V substrate, possibly by enhanced interfacial bonding, mechanical interlocking, and stress relief.

► Nanodiamond particles were deposited on Ti6Al4V before DLC deposition.
► Diamond/DLC composite film was formed by incorporation of nanodiamond particles.
► Greatly enhanced adhesion of diamond/DLC composite film on Ti6Al4V was achieved.
► Enhanced adhesion is by increased interfacial bonding and mechanical interlocking.